Recessed downlight luminaires are extremely popular due to their unobstructive, hidden nature within a ceiling and the versatility provided by the various types of downlights available. Downlights may be used to provide wall wash, normal downlight or highlight a specific area.
As the popularity of these luminaires has grown, improvements have been continually made to improve the operating efficiency and lighting characteristics. For example, downlights have been developed to operate with compact fluorescent lamps (CFLs). Even more efficient than CFLs, it would be desirable to develop downlights to operate specifically with light emitting diodes (LEDs). However, when LEDs are positioned in deep round reflectors, there is a propensity to have a dark area in the center of a light dispersion graph. As shown in FIG. 1, the center area beneath the downlight indicates a sharp decrease in illumination at the center of the light distribution pattern. It would be desirable to redirect some light toward the center of the light distribution pattern to provide more uniform illumination on a work plane.
Another area of desired improvement is with operating efficiency. In general, LEDs have the potential to provide a higher efficiency and longer life than other light sources. LEDs have a higher operating efficiency in part due to cooler operating temperatures. Moreover, LEDs do not burn out like incandescent bulbs, but instead dim over the course of their life. When LEDs operate at cooler temperatures, they operate more efficiently, meaning higher light output for given input energy. Additionally, with more efficient operation at cooler temperatures, the LEDs have longer life. As temperatures increase however, the efficiency decreases and the life is reduced.
Downlights are typically positioned in a plenum or similar volume above a ceiling. Since this plenum area is typically enclosed, the heat from the downlight has a tendency to build up and over a period of time and the temperature is higher than the temperature below, in the illuminated area. Since the illuminated area below the light is cooler than the volume above, it would be desirable, from an operating efficiency perspective, to transfer some heat to this area beneath the luminaire in order improve LED performance and life.
Given the foregoing deficiencies, it would be desirable to overcome the above and other deficiencies.